In general, a fluorine resin has an excellent resistance to solvent attach and does not have a water-absorption property. Further, of various synthetic resins, the fluorine resin has very excellent weatherability, heat resistance, abrasion resistance and non-tackiness.
Polytetrafluoroethylene (PTFE) is the representative polymer of the fluorine resin. PTFE is used as a corrosion resistant material for inner lining or packings in pipes of chemical apparatuses from the standpoints of a high heat resistance and an excellent resistance to solvent attack; an insulating material for electric cables from the standpoints of a low dielectric constant and dielectric loss and a high resistivity; and a bearing or sliding material of non-oil supply from the standpoint of an excellent surface lubricating property.
However, since PTFE has a high melting point and it is difficult for PTFE to fuse by heating, the moldability is poor and the molding must be conducted by a sinter molding. Therefore, the moldability of PTFE has been improved by using a copolymer comprising tetrafluoroethylene and a fluorine-containing vinyl monomer other than the tetrafluoroethylene or olefin monomer, or a fluorine resin which does not use tetrafluoroethylene. Thereby, a thermoplastic material having the characteristics of PTFE has been obtained.
On the other hand, the fluorine resin has the above-described excellent characteristics but is expensive, and it is therefore considered that a composite of the fluorine resin and other inexpensive material is useful from the practical standpoint.
However, the fluorine resin has a very low solubility parameter which is the measure for compatibility as compared with other resins and it is difficult for the fluorine resin to compatibilize with other resins. In particular, investigations are not substantially made on the compatibility of the fluorine resin with an olefin polymer which is inexpensive and is widely used and has excellent mechanical characteristics and processability.
A thermoplastic polyurethane or polyalkyl methacrylates are known as a resin having a certain extent of the compatibility with the fluorine resin. However, those resins are expensive as compared with the olefin polymer or show decrease of the tensile elongation which is the important factor as the mechanical characteristics. Thus, those resins are not satisfactory as the materials to be used together with the fluorine resin. Further, there is a method of blending the fluorine resin with a copolymer of an alkyl methacrylate and an olefin, but this method is not general and the effect on the compatibility is not sufficient.